Test all of your software. Make sure that your engine of choice is installed and configured as needed. The same goes for any tools you’ll use for making art, music, and sound effects. Avoid any last minute OS or software updates, unless absolutely necessary. It’s not strictly required, but if you have a spare computer, consider duplicating your setup there also. It’s nice to know that if you run into a hardware or software issue that you can just switch machines and figure it out after the jam.

Have some kind of backup system in place. Strongly consider using a version control system. Personally, I like Mercurial, but there are a ton of good choices. Periodically copying your entire project file into Dropbox is also an option. I really don’t like that approach for longer-term projects, but it’s fine for a jam, and it’s much quicker to set up.

Test your web hosting before the jam starts, not when you’re exhausted and time is almost up. (Ask me how I know this.) Do a dummy build of a “Hello World” type project and put it online. Test it in multiple browsers (if doing a web build) and from a couple of different machines. Also consider doing Windows and OS/X builds in addition to your web builds.

Have plenty of graph paper, pens, post-it’s, index cards, etc. handy. That way you can quickly sketch out ideas and maybe even build a paper prototype.

Don’t go overboard on cramming. There are things you know, and things you don’t, and that’s okay. I learned in music college that sometimes an hour of sleep is much more valuable than an hour of practice. Brush up on your skills if you want, but don’t forget to take time to relax and to get a lot of extra sleep.

Finally, get out of the house and do something fun, preferably with any family or friends who you may be neglecting during the jam weekend. This will help you to go into the jam feeling rested, relaxed, and ready for some game dev.